Having spent $24 million building machines that extract oil out of water, Kevin Costner hopes to help clean up the Gulf Coast. TIME looks at some of the most philanthropic celebrities and their causes.

Kevin Costner

By Nate RawlingsMonday, June 28, 2010

Joshua Roberts / Reuters

In 1995, Kevin Costner directed and starred in Waterworld, a post-apocalyptic nightmare fantasy that became an actual nightmare after the $175 million blockbuster-in-waiting grossed a mere $88 million domestically. But while working on Waterworld, Costner learned about Ocean Therapy Solutions (OTS), a company working on a Department of Energy grant to develop centrifugal oil-water separators. The company, which he bought for $24 million, found little interest in its products until the Deepwater Horizon disaster. The largest machine, the V20, can clean 210,000 gallons of oily water each day to 97 percent purity. To bring attention to the machines, Costner testified before Congress, telling lawmakers, "I believe this machine, made over 12 years ago with all the care, science, and money that I could throw at it, is one major solve in this giant puzzle." He traveled to New Orleans and demonstrated the machine for local officials. On June 18, BP announced that it had purchased 32 machines for immediate use in the Gulf.